Final answer:
The conjugate acid for H₂O is the hydronium ion, H₃O+. Water becomes a hydronium ion by attracting an additional proton and forming a molecule with three hydrogen atoms, one oxygen atom, and a + charge.
Step-by-step explanation:
The conjugate acid for the acid H₂O is the hydronium ion, H₃O+. When water (₂O) donates a proton (H+), it becomes its conjugate base OH−. Conversely, when H₂O attracts an additional proton (H+), it forms hydronium ion (H₃O+) which is its conjugate acid.
To draw the Lewis structure for hydronium ion, start with a central oxygen atom and attach three hydrogen atoms through single bonds. The oxygen atom will also have a non-bonding pair of electrons, and there will be a + charge to represent the extra proton gained.
The chemical reaction between water acting as an acid and NH3 (ammonia) acting as a base produces the conjugate base OH− and the conjugate acid NH4+. This demonstrates the dynamic nature of acid-base reactions where water can act as either an acid or a base.